Computed thermodynamic stabilities of silylium Lewis base adducts

2018 ◽  
Vol 16 (13) ◽  
pp. 2318-2323 ◽  
Author(s):  
Christina A. Roselli ◽  
Michel R. Gagné
Keyword(s):  
Computational Study ◽  
Lewis Base ◽  
Lewis Bases

We report a computational study of the transfer of silylium from phosphine to heteroatom containing Lewis bases including ethers, phosphines, and amines.

Exchange of Cl+ between Lone-Pair Donors and π-Donors: A Computational Study

2000 ◽  
Vol 6 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Theis I. Sølling ◽  
Leo Radom
Keyword(s):  
Ab Initio ◽  
Computational Study ◽  
Lone Pair ◽  
Binding Energies ◽  
Lewis Base ◽  
Molecular Orbital Calculations ◽  
Reaction Energy ◽  
Lewis Bases ◽  
Donor Ability ◽  
Reaction Energies

The chemistry of mono-adducts ([Cl–X]+) between Cl+ and a Lewis base (X = NH3, H2O, HF, PH3, H2S or HCl) has been investigated using ab initio molecular orbital calculations at the G2 level. The reactions of such mono-adducts with additional Lewis bases (Y) are found to give [Y–Cl]+ plus X, generally without an intermediate barrier, via a bis-adduct [Y–Cl–X]+. The binding energies of the bis-adduct and the reaction energies are related to the donor properties of the Lewis bases. The reactions between the mono-adducts [Cl–X]+ and the π-donors ethylene and acetylene yield chloriranium and chlorirenium ions, respectively. These reactions proceed via complexes that resemble either the reactants or products depending on the sign of the reaction energy, the latter in turn being determined by the donor ability of the Lewis base. Results for the chlorine systems are compared with those for the corresponding phosphorus systems investigated previously.

scholarly journals Relativistic Effects on NMR Parameters of Halogen-Bonded Complexes

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4399 ◽  
Author(s):  
Ibon Alkorta ◽  
José Elguero ◽  
Manuel Yáñez ◽  
Otilia Mó ◽  
M. Merced Montero-Campillo
Keyword(s):  
Relativistic Effects ◽  
Lewis Base ◽  
Coupling Constants ◽  
Basic Site ◽  
Lewis Bases ◽  
Nmr Parameters ◽  
Quadrupolar Coupling ◽  
Binary Complexes ◽  
Computational Level ◽  
Bonded Complexes

Relativistic effects are found to be important for the estimation of NMR parameters in halogen-bonded complexes, mainly when they involve the heavier elements, iodine and astatine. A detailed study of 60 binary complexes formed between dihalogen molecules (XY with X, Y = F, Cl, Br, I and At) and four Lewis bases (NH3, H2O, PH3 and SH2) was carried out at the MP2/aug-cc-pVTZ/aug-cc-pVTZ-PP computational level to show the extent of these effects. The NMR parameters (shielding and nuclear quadrupolar coupling constants) were computed using the relativistic Hamiltonian ZORA and compared to the values obtained with a non-relativistic Hamiltonian. The results show a mixture of the importance of the relativistic corrections as both the size of the halogen atom and the proximity of this atom to the basic site of the Lewis base increase.

scholarly journals 5-Nitrosalicylic Acid and its Proton-Transfer Compounds with Aliphatic Lewis Bases

2005 ◽  
Vol 58 (1) ◽  
pp. 47 ◽  
Author(s):  
Graham Smith ◽  
Andy W. Hartono ◽  
Urs D. Wermuth ◽  
Peter C. Healy ◽  
Jonathan M. White ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Lewis Base ◽  
Unusual Structure ◽  
Lewis Bases ◽  
Carboxylate Oxygen ◽  
Hydrogen Bonding Interactions ◽  
Polymer Compound ◽  
Proton Transfer Compounds ◽  
Centrosymmetric Dimers

The crystal structures of the proton-transfer compounds of 5-nitrosalicylic acid (5-nsa) with morpholine (morph), hexamethylenetetramine (hmt), and ethylenediamine (en) have been determined and their solid-state packing structures described. The compounds are [(morph)+(5-nsa)–] 1, [(hmt)+(5-nsa)–·H2O] 2, and [(en)2+2(5-nsa)–·H2O] 3. In all compounds, protonation of the hetero-nitrogen of the Lewis base occurs. With 1, the 5-nsa anions and the morpholine cations lie, respectively, in or across crystallographic mirror planes and are linked within the planes by hydrogen-bonding interactions through the aminium group and the carboxylic and phenolic oxygens of the anionic 5-nsa species giving a two-dimensional sheet polymer. Compound 2 is an unusual structure with the planar 5-nsa anions lying within pseudo mirror planes and cyclically linked by duplex water bridges through a single carboxylate oxygen into centrosymmetric dimers. The hmt cation molecules are disordered across the pseudo mirror and are strongly linked by N+–H···O hydrogen bonds only to the water molecules with peripheral weak hmt C–H···O hydrogen bonds extending the dimer within and between the dimer planes. Compound 3 is a network polymer comprised of the 5-nsa anions, the en dianions, and the water molecule in an extensive hydrogen-bonded structure.

scholarly journals Recent Synthesis Developments of Organoboron Compounds via Metal-Free Catalytic Borylation of Alkynes and Alkenes

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 101 ◽  
Author(s):  
Yanmei Wen ◽  
Chunmei Deng ◽  
Jianying Xie ◽  
Xinhuang Kang
Keyword(s):  
Lewis Acids ◽  
Heterocyclic Carbenes ◽  
Lewis Base ◽  
Organoboron Compounds ◽  
Lewis Bases ◽  
Metal Free ◽  
Recent Synthesis

Diboron reagents have been traditionally regarded as “Lewis acids”, which can react with simple Lewis base to create a significant nucleophilic character in one of boryl moieties. In particular, bis(pinacolato)diboron (B2pin2) reacts with simple Lewis bases, such as N-heterocyclic carbenes (NHCs), phosphines and alkoxides. This review focuses on the application of trivalent nucleophilic boryl synthon in the selective preparation of organoboron compounds, mainly through metal-free catalytic diboration and the β-boration reactions of alkynes and alkenes.

Dioxouranium(VI) complexes with N-salicylsalicylaldimines and their Lewis base adducts

1975 ◽  
Vol 28 (4) ◽  
pp. 885 ◽  
Author(s):  
ATT Hsieh ◽  
RM Sheahan ◽  
BO West
Keyword(s):  
Schiff Bases ◽  
Metal Atom ◽  
Lewis Base ◽  
Donor Ligands ◽  
Chelate Complexes ◽  
Nitrogen Donor Ligands ◽  
Uranium Metal ◽  
Lewis Bases ◽  
Nitrogen Donor ◽  
Weak Coordination

New dioxouranium(VI) complexes with the dibasic terdentate Schiff bases, XC6H3(2-OH)CH=N-CH2C6H4(2?-OH) (X = H, 5-Cl or 3-MeO), have been synthesized and characterized as their 1 : 1 alcohol adducts. The labile alcohol molecules in these complexes are readily replaced by various oxygen or nitrogen donor ligands, affording six- or seven- coordinate complexes. Evidence is presented for the rather weak coordination of these Lewis bases to the uranium metal atom. The various possible conformations for these [6,6]-membered chelate complexes are also discussed.

scholarly journals On the Bonding Situation in Stannocene and Plumbocene N-Heterocyclic Carbene Complexes

2019 ◽  
Author(s):  
Diego Andrada ◽  
Sergi Danés ◽  
Lisa Wirtz ◽  
Carsten Mueller ◽  
Volker Huch ◽  
...  
Keyword(s):  
Computational Study ◽  
Decomposition Analysis ◽  
Heterocyclic Carbenes ◽  
Lewis Base ◽  
Energy Decomposition Analysis ◽  
Dispersion Interactions ◽  
X Ray Diffraction ◽  
Group 14 ◽  
Carbene Complexes ◽  
Covalent Interactions

A detailed experimental and computational study of a series of stannocene and plumbocene N-heterocyclic carbene complexes is presented. This unique class of group 14 Lewis acid base adducts was obtained from reactions of the corresponding metallocenes and N-heterocyclic carbenes (NHC), and were structurally characterized by single crystal X-ray diffraction. The obtained structures show a perpendicular pose of the NHC with respect to the metallocene, hence precluding the maximal interaction between the moieties. The nature of the Sn-CNHC and Pb-CNHC bonds have been investigated by applying Energy Decomposition Analysis (EDA-NOCV). For the sake of comparison, known stannocene and plumbocene Lewis base complexes have been included in the series. The attractive chemical bonding interactions are around 50% electrostatic, 30% covalent and 20% dispersion. Indeed, dispersion interactions play a determining role the bigger the substituents become. The covalent interactions derive from the donation of the carbene ligand into the empty p orbital of the metallocene.

scholarly journals On the Aggregation and Sensing Properties of Zinc(II) Schiff-Base Complexes of Salen-Type Ligands

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2514 ◽  
Author(s):  
Consiglio ◽  
Oliveri ◽  
Failla ◽  
Di Bella
Keyword(s):  
Schiff Base ◽  
Schiff Bases ◽  
Coordination Compounds ◽  
Cell Imaging ◽  
Spectroscopic Properties ◽  
Lewis Base ◽  
Schiff Base Complexes ◽  
Sensing Properties ◽  
Lewis Bases

The zinc(II) ion forms stable complexes with a wide variety of ligands, but those related to Schiff-bases are among the most largely investigated. This review deals with the peculiar aggregation characteristics of Zn(II) Schiff-base complexes from tetradentate N2O2 salen-type ligands, L, derivatives from salicylaldehydes and 1,2-diamines, and is mostly focused on their spectroscopic properties in solution. Thanks to their Lewis acidic character, ZnL complexes show interesting structural, nanostructural, and aggregation/deaggregation properties in relation to the absence/presence of a Lewis base. Deaggregation of these complexes is accompanied by relevant changes of their spectroscopic properties that can appropriately be exploited for sensing Lewis bases. Thus, ZnL complexes have been investigated as chromogenic and fluorogenic chemosensors of charged and neutral Lewis bases, including cell imaging, and have shown to be selective and sensitive to the Lewis basicity of the involved species. From these studies emerges that these popular, Lewis acidic bis(salicylaldiminato)Zn(II) Schiff-base complexes represent classical coordination compounds for modern applications.

scholarly journals An Investigation of the Organoborane/Lewis Base Pairs on the Copolymerization of Propylene Oxide with Succinic Anhydride

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 253 ◽  
Author(s):  
Lan-Fang Hu ◽  
Dan-Jing Chen ◽  
Jia-Liang Yang ◽  
Xing-Hong Zhang
Keyword(s):  
Propylene Oxide ◽  
Succinic Anhydride ◽  
Lewis Base ◽  
Molar Ratio ◽  
Base Pairs ◽  
Catalytic Systems ◽  
Aliphatic Polyesters ◽  
Lewis Bases ◽  
Molecular Weights ◽  
High Ester

The copolymerization of biorenewable succinic anhydride (SA) with propylene oxide (PO) is a promising way to synthesize biodegradable aliphatic polyesters. However, the catalytic systems for this reaction still deserve to be explored because the catalytic activity of the reported catalysts and the molecular weights of produced polyesters are unsatisfied. Herein, we investigate the copolymerization of SA with PO catalyzed by the organoborane/base pairs. The types of Lewis bases, organoboranes, and their loadings all have a large impact on the activity and selectivity of the copolymerization. High ester content of >99% was achieved when performed the PO/SA copolymerization using triethyl borane (TEB)/phosphazene base P1-t-Bu (t-BuP1) pair with a molar ratio of 1/1 at 30–80 °C. Using TEB/t-BuP1 pair with the molar ratio of 4/1 at 80 °C, the turnover of frequency (TOF) was up to 128 h−1 and clearly higher than the known TOF values (0.5–34 h−1) of the PO/SA copolymerization by previously reported catalysts. The number-average molecular weights (Mns) of the resultant polyesters reached up to 20.4 kg/mol when copolymerization was carried out using TEB/t-BuP1 (1/1, in molar ratio) at 30 °C.

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